Sheet material perforating apparatus



G. F. WALES SHEET MATERIAL PERFORATING APPARATUS Dec. 9, 1941.

Filed Feb. 18, L941 INVENTOR ATI'ORNEYS Patented Dec. 9, 1941 SHEET MATERIAL PEBFORATING APPARATUS George F. Wales, Buffalo, N. Y. Application February 18, 1941, Serial No. 379,447

3 Claims.

This invention relates to a sheet material perforating apparatus of the general character shown in United States Patent No. 1,955,866 and more particularly to the punching unit of the same.

Ithas been found that prior devices of a similar construction were so organized that the-same were unduly wide and thus limited the closeness which it was possible, to form holes adjacent to one another in a workpiece by one operation of a press.

The object of the present invention is to provide a hole punching apparatus which is comparatively narrow and thereby permit a number of such units to be mounted close together vin a press for forming a plurality of closely spaced holes in a workpiece of sheet material by one operation of the press.

In the accompanying drawing;

Fig. 1 is a side elevation, partly in section, of a perforating apparatus embodying a satisfactory form of this invention.

Fig. 2 is a horizontal section of the same, taken on line 22, Fig. 1.

In the following description the same reference characters indicate corresponding parts in both figures of the drawing.

The holder upon which the working parts of this perforating apparatus are mounted may be of any suitable construction that shown in the drawing, as an example, consisting of a lower base orshoe l and an upper horn orhead II which overhangs the base and is separated therefrom by an intervening gap l2 for the reception of the sheet material workpiece, such as a sheet of metal which is to be perforated.

The holder is held in place in the press during the perforating operation by means of a 'templet plate I l which rests on the bed l5 of the press and is secured to the underside of the holder base by screws 9 and properly located thereon by a locating screw I6 arranged on the base and engaging with a locating opening ll in the templet plate.

On its upper side the base is provided with a seat or socket l8 which receives a button shaped die l9 and the slug which is removed from the workpiece when forming the hole therein is carried away from the interior of the hollow die by a chute 20 in the base. Above the die and axially in vertical alinement therewith the horn of the holder is provided with a vertical guide opening 2|.

The numeral 22 represents the cylindrical body the guide opening 2| provided at its lower part.

with a cutting edge or hit 23 which is adapted to cooperate with the die I9 for producing a hole in the workpiece. At its upper end the body of the punch is provided with a head 24 which together with the punch body are adapted to be engaged by the vertically movable ram 25 of the press and moved downwardly relative to the die. The lower part of the punch body is arranged axially within a vertical guide sleeve which has a large diameter lower part 26 slidable vertically in the guide opening 2| of the holder horn and a relatively small diameter upper part 21 whereby an upwardly facing shoulder. is formed between the large lower and small upper parts of the guide sleeve, asshown in Fig. 1. The upper parts of the guide sleeve and the punch body are surrounded by a helical stripping spring 29 which bears at its lower end against the shoulder 28 of the guide sleeve and at its upper end against the underside of the punch head.

The guide sleeve is yieldingly held in its lowered position by a retaining spring 30 which is preferably constructed in the form of a leaf and connected at one of its ends to the upper side of the holder by means of screws 3| while its opposite end engages with the upper-side of the lowermost turn of the strippingspring.

When no sheet metal workpiece is present between the die and the punch body and guide sleeve the latter is in its lowermost position and engages its lower end with the top of the die.

. When it is desired to perforate a sheet the latter is pushed between the opposing ends of the die and guide sleeve which is possible due to the chamfered or bevelled upper edge 32 on the die and the chamfered or rounded lower edge 33 on the guide sleeve. As the ram descends after the workpiece has been inserted between the die and guide sleeve the head and body of the punch are depressed by engagement of the ram with the upper end of the same so that the lower cutting or hit end of the punch body engages the workpiece and forms a hole therein by removing a slug from the workpiece, which slug is discharged through the chute 20. During the descent of the ram and punch the stripping spring 29 is compressed but during the ascent of the ram and the punch the latter is elevated by of the punch which is arranged axially within the resilience of the stripping spring 29 and its bit or cutting end is lifted and stripped from the perforation which has just been formed in the workpiece. As the ram rises the guide sleeve and stripping spring are prevented from jumping out of the guide opening 2| in the holder tocooperate with said dieand "having headatgether with the punch due to the reaction of the stripping spring by means of the retaining spring 30 which bears downwardly on the lower coil or convolution of the stripping spring, thereby maintaining the parts intheir proper position for operating efilciently.

By employing a guide sleeve having a lower part guided in the holder and an upper part which extends above the holder it is possible to make the punch of comparatively small diameter and of considerable length and thereby guide'the same efllciently so that it is not liable to tilt sidewise and bind in the guide sleeve and thus permit of making the perforating unit as a whole comparatively narrow and render it possible. to punch holes closer together in a workpiece than has been possible by a single operation in perforating apparatus of the type heretofore known when a plurality of such units have to be arranged side by side.

Obviously the retaining spring 30 may be deflected downwardly during the perforating operation and thus serve to lift the guide sleeve 26 in addition to preventing it from jumping out of the guide opening during the return move-' ment of the perforating mechanism.

I claim as my invention:

1. An apparatus for perforating sheet material comprising a holder provided on its, lower part with a die and on its upper part with a vertical guide opening which is in line with the die, and

a punching unit including a single guide sleeve having a lower part of comparatively large diameter which slides in said opening and an upper part of comparatively small dameter arranged above the holderand forming an upwardly lacing shoulder between the large lower part and the small upper part of the sleeve, a punch having a body slidable in said sleeve and provided at its lower end with a cutting edge adapted to the upper end of said body, and a'stripping spring surrounding the upper parts of said punch body and guide sleeve above the holderand hearing at its lower end directly' against said shoulder and at its upper end againstsaid head.

rial comprising a holder provided on its lower part with a die and on'its ,upper part with a vertical guide opening which is. ll line with the die, and a punching unit including a guide sleeve having a large lower part which slides in said opening and a narrowerupper .part'arranged above the holder and forming an upwardly 'facing shoulder between the-large lower part and narrow upper part 01 the sleeve, a punch-having a body slidable in said sleeve" and provided at its 'lower end with a cutting edge adapted to cooperate with said die and having a head at the upper end of said body, a stripping spring surrounding the upper parts of said punch body and guide sleeve and bearing at its lower and upper ends against said shoulder and head and a leafshaped retaining spring secured at one end to said holder and engaging its opposite end with said stripping spring.

3. An apparatus for perforating sheet material comprising a holder provided on its lower partwith a die and on its upper part with a I GEORGE 1". WALES. 

